The risks and dangers associated with yawing trailers during descent at certain speeds and other driving conditions are well-known. Some conditions may even cause the trailer to tip or shift sideways or cause the yawing or swaying motion of the trailer to become uncontrollably divergent, which may result in the trailer becoming “jackknifed”.
Some devices exist for limiting the yawing motion of the trailer, such as telescoping lateral arms with damping effects. These arms are attached along the coupling on either side with a ball and socket connection at one extremity on the rear of the vehicle, and are attached to the coupling with a ball and socket connection at the other extremity. Another device is a flexible curvilinear damping mechanism as described in U.S. Pat. No. 6,688,631 to Andre. One drawback of these devices is that they are continually active, require routine maintenance, and tend to wear out and need to be replaced long before the operational lives of the vehicle-trailer and/or the hitch assembly have expired.
There have also been passive devices and systems for at least detecting a swaying motion of the trailer in a vehicle-trailer combination, many of which involve a non-contact means such as camera, ultra sound device, radar, laser, inertial, and/or magnetic sway sensors. One type of inertial sensor is a mercury sensor mounted in the towing vehicle as described in U.S. Pat. No. 4,254,998. One type of magnetic sway sensor mounted on the trailer or towed vehicle is described in U.S. Pat. No. 3,810,521. Because hitch mechanisms are exposed to weather, road debris, and other harsh aspects of the environment, these passive type devices and systems may typically lack robustness, which in turn necessitates frequent maintenance and replacement. In addition, these passive type devices and systems are often quite expensive or technically complex both in terms of construction and installation.
Many of the foregoing devices and systems attempt to measure the dynamic hitch or sway angle of the trailer to regulate vehicle dynamics. Some of these systems propose methods of evaluating the dynamic hitch or sway angle with a type of trailer motion control algorithm in an attempt to control the vehicle-trailer stability and ultimately to prevent jackknifing.
It would be desirable to have a device or system for detecting a yaw angle of the trailer relative to the vehicle while overcoming some of the aforementioned drawbacks. It is further desirable that the device or system for detecting the yaw angle of the trailer be more robust, easy to install on an existing hitch assembly, and relatively less expensive.